So how can the phone company not backtrack to figure out where the call originated? They know that at a specific time they connected a call to your number. If the call didn't originate on their network, don't they know whose network they're forwarding it from? If so, couldn't they then contact that network and see where it originated from (possibly going to other networks, maybe outside the country) and still trace it back to some originating phone line somewhere in the world? I mean, I can guess that they wouldn't keep these logs for very long because they'd get big very quickly, but even keeping it for 15 minutes and allowing you to call a number and say, "Hey this was a junk call" would help.

In fact, I once got a new phone number that was previously owned by someone who owed a lot of people money. I was getting regular harassing calls from debt collectors who didn't believe that I was the new owner of the number. So I called the police and filed a report. I then called the phone company and gave them the number of the police report, and they gave me a phone number to call a few minutes after each time the debt collectors would call me. After 2 or 3 calls, they had the contact info of the debt collectors, gave it to the police who contacted the debt collectors and I never heard from them again.

Why can't this approach work for scam calls? I mean if they're outside the country, it would involve more work, but if thousands or millions of people are reporting calls that originate from the same place, then it seems like it would rise to the level of being worth it to do something about it.

Obviously the phone company knows everything. Whether they'll act on your call is the question. Not sure if dialing *57 (Malicious call reporting [0]) will work on a cell phone, but there's probably a fee.

[0] https://en.wikipedia.org/wiki/Vertical_service_code